The objectives of this study are a) to compare the behavioral development of preterm and term infants over the first 18 months of life; b) to determine the predictive validity of the Brazelton Neonatal Behavioral Assessment; and c) to compare the assessments' effectiveness to neurologically weighted assessment procedures. Thirty fullterm and thirty preterm infants will be used as subjects. Both groups will be assessed with Parmelee's set of obstetric, pediatric scales, and his neurological examination during the neonatal period and repeatedly over the next 18 months post-conceptual age. The Brazelton scale will be administered repeatedly during the neonatal period. Behavioral assessments of cognitive, emotional, and social development including videotaped face-to-face infant-mother interactions, Casati-Lezine and Bayley scales, free field play, and home observations will be made repeatedly over the first 18 months post-term conceptual age. Data analysis of assessed outcome in relationship to the neonatal data and the relationship among the other ages of assessment will provide an evaluation of the differences in the groups, the effectiveness of the scale, and the patterns of development in these infants.